1. Field of the Invention
The present invention relates to a semiconductor device and an operation mode setting method for the semiconductor device. More specifically, the present invention relates to a semiconductor device that switches operation modes based on the presence or absence of bonding and an operation mode setting method for the semiconductor device.
2. Description of the Related Art
It is a common practice to form circuits for implementing different functions on a substrate (chip) in advance, select a specific function that meets the user's (customer's) request upon assembly into a semiconductor device, and customize the semiconductor device by activating a circuit that has the selected function. With this, a semiconductor device that fulfils customers' individual requests can be manufactured while reducing the total manufacture cost by making a general-purpose chip.
U.S. Pat. No. 5,754,879 describes a technology of selecting any one of multiple operation modes based on whether or not an external terminal (power supply external terminal, ground external terminal, or reset external terminal) is bonded to an internal terminal (mode pad), which is provided on a chip for operation mode selection. This technology enables a semiconductor device to select an operation mode merely from the presence or absence of bonding without newly installing an external terminal through which special signals for operation mode selection are supplied.
The inventor of the present invention has recognized that the premise of the technology described in U.S. Pat. No. 5,754,879 resides in that the voltage (logical level) input to a mode pad from the outside is determined in advance. In other words, whether an operation mode is selected at the H level or the L level is determined for each mode pad in advance. This means that each mode pad has to be placed adjacent to a specific internal terminal (power supply pad, ground pad, or reset pad) connected by a bonding wire to a specific external terminal (power supply external terminal, ground external terminal, or reset external terminal). In short, mode pads are arranged under layout limitations.